Expander Brake Baffles for Thermal Isolation

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Solution Overview

Problem

Large pneumatic brake/clutch devices face temperature limitations due to the inflatable ring material, restricting the maximum surface temperature of the drum and thus the power transmission capacity, as the inflatable ring overheats at temperatures above 250° F (121° C).

Innovation Solution

Incorporating baffles between arcuate backing blocks to create a tortuous path for radiant heat, preventing it from directly reaching the inflatable ring, allowing the friction surface to operate at higher temperatures without overheating the inflatable ring.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If the drum friction surface temperature is increased to transmit more power, then the power transmission capacity increases, but the inflatable ring temperature exceeds its service limiting temperature

Engineering Contradiction:

Improvepower transmission capacityVSAvoidinflatable ring temperature

Core Design Contradiction:

PowerVSTemperature

Solution Approach 1:

Radiant barriers are introduced as intermediary elements positioned between the drum friction surface and the inflatable ring. These barriers intercept and reflect radiant heat energy, preventing it from directly heating the inflatable ring. This allows the drum friction surface to operate at higher temperatures for increased power transmission while the inflatable ring remains below its service limiting temperature

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The harmful radiant heat energy is extracted from the direct path between the drum friction surface and the inflatable ring by using radiant barriers. The barriers capture and redirect the radiant energy away from the inflatable ring, effectively removing the thermal coupling that previously limited power transmission capacity

Inventive Principle:

Principle #2Taking out (Extraction)

2Loss of energy

If the drum friction surface temperature is increased to dissipate more power, then the power dissipation capacity increases, but the inflatable ring overheats above 250° F

Engineering Contradiction:

Improvepower dissipation capacityVSAvoidinflatable ring temperature

Core Design Contradiction:

Loss of energyVSTemperature

Solution Approach 1:

Radiant barriers serve as intermediary elements that intercept radiant heat from the drum friction surface during power dissipation operations. By reflecting this radiant energy away from the inflatable ring, the barriers enable higher power dissipation capacities while maintaining the inflatable ring temperature below its 250° F service limit

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The radiant heat energy, which previously represented a harmful effect limiting power dissipation capacity, is converted into a beneficial situation where the heat is redirected and contained away from the inflatable ring. This allows the system to exploit the full thermal capacity of the drum friction surface for power dissipation without compromising the inflatable ring

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This solution enables the friction surface to reach 1200° F (648° C) without exceeding the inflatable's temperature limit, increasing power transmission capacity by 40% without enlarging the brake/clutch assembly.

Implementation Method 1

The baffles prevent the radiant heat emanating from the friction surface on the first power transmission member from emanating radially outwardly and irradiating or heating the inflatable rubber expander ring

Methodology Applied

Scientific EffectThermal radiation: Thermal Radiation

Data Source

PatentUS8967356B2Expander brake/clutch assembly and method of making same

Publication Date: 2015.03.03 DANFOSS AS

AI summary

A pneumatic expander brake/clutch having a first power transmission member as a drum with an annular friction surface on the outer periphery. Arcuate backing block segments are circumferentially closely spaced and adjacent about the drum friction surface. The backing blocks have brake friction pads on the radially inner surface. An inflatable expander ring surrounds the backing blocks and upon inflation forces the blocks radially inward and the pads against the drum friction surface. Baffles are provided on the end of the backing blocks and extend into the spaces between circumferentially adjacent blocks to form a tortuous path for heat emanating from the drum friction surface in a radially outer direction. The baffles insulate the inflatable expander from heat which permits the drum friction surface to operate at a higher temperature, and power transmission/dissipation without overheating the expander.